A pulse radar for investigating an object in space by using conventionally known pulse waves basically has a construction as shown in FIG. 14.
That is, in this pulse radar 10 shown in FIG. 14, upon the receipt of a trigger signal G outputted in a predetermined cycle Tg from a control section 16 described later, a transmitter section 11 generates a pulse wave Pt having a predetermined width and a predetermined carrier frequency synchronized with the trigger signal G and radiates the generated pulse wave to a space via a transmitter antenna 11a. 
This pulse wave Pt is reflected by means of an object 1a which exists in a space 1, and its reflection wave Pr is received by a receiver antenna 12a of a receiver section 12, and then, the received wave is detected by means of a detector circuit 13.
A signal processor section 15 analyzes the object 1a which exists in the space 1 based on a timing with which a detected output D is outputted from the receiver section 12 while a timing with which a pulse wave is transmitted from the transmitter section 11 is defined as a reference timing, for example, or its outputted waveform.
The control section 16 makes a variety of controls with respect to the transmitter section 11 and the receiver section 12 based on a processing result or the like of the signal processor section 15.
A basic construction of such pulse radars 10 is disclosed in patent documents 1 and 2 below.
Patent document 1: Jpn. Pat. Appln. KOKAI Publication No. 7-012921
Patent document 2: Jpn. Pat. Appln. KOKAI Publication No. 8-313619
From among the pulse radars having such a basic construction, the following two types of pulse radars are devised as automotive radars which have been practically available in recent years.
The development of pulse radars of a first type is underway for the purpose of assistance at the time of high speed running such as prevention of collision of automobiles or running control by investigating a narrow angle range with high output and in long distance using a millimeter wave band (77 GHz).
The development of pulse radars of a second type is underway for the purpose of assistance at the time of low speed running such as automobile dead angle assistance or assistance of putting a car in garage by investigating a wide angle range with low output and in long distance using a quasi millimeter wave (22 GHz to 29 GHz).
The quasi millimeter band for use in the pulse radars of this second type is generally referred to as an UWB (Ultra-wideband), and is used for medical radars, radars for walk assistance of visually handicapped persons, or a short distance communication system or the like as well as automotive radars.
The UWB is a wide bandwidth, and thus, in a radar system, a short pulse having a width shorter than 1 ns can be used, and it is expected that short range radars having high distance resolution can be achieved.